andyk

I've fixed this now. Quite separately I had a problem with low (less than 500k) network throughput. After having tried various remedies I found that setting my card from 'Auto' to '100M full duplex' solved the problem. Since then I've also had no further problems with dwm and high cpu / dpc.

OK and thanks for all your help.

Thanks a ton for deciphering the cause. Really frustrating. I find it almost unbelievable that MS ships a product that can't use it as, to quote PassMark, "The low to mid range chart typically contains video cards that are a couple of years old and includes . . . better performing Integrated Display Adapters from Intel, Asus and other manufacturers." Anyway PassMark gives the GeForce 210 a score of 184 which is half way down the chart. How much faster do I need to go? Andy PS. Found this thread with similar issues to mine and which I see you contributed to. https://social.technet.microsoft.com/Forums/windows/en-US/6884366d-6759-4ab9-89c5-fd6af8008b28/dwmexe-starts-consuming-lots-of-cpu-when-machine-is-idle?forum=w8itproperf

Andre Here it is. https://drive.google.com/file/d/0B519kC-I-qWkLXBkVUEwR3FySWc/view?usp=sharing Andy

Hi Andre I hope you can help me. I installed Win8.1 x64 on my 4 core 16GB machine (c 2007) and since then have had dwm.exe exhibit 20% CPU for a couple of minutes every 7 mins or so. My machine is normally fine for the first day after a reboot but it gets steadily worse. Shutting down Outlook seems to immediately stop dwm's high CPU but it may be memory related (even though I rarely exceed 12GB) or GDI as sometimes shutting down Chrome (with typically 20+ windows open) also does the same. I also normally have 15+ applications running concurrently. I have just replaced the GE7300 with a GE210 and it made no difference. I started researching this a month or so ago and have used LatenecyMon and xperf. They both point to nvlddmkm.sys being the culprit. Here's an edited xperf showing the modules with >256us. This trace was taken during one of the high CPU dwm periods. Total = 11946 for module ndis.sysElapsed Time, > 256 usecs AND <= 512 usecs, 11, or 0.09% Total = 100191 for module nvlddmkm.sysElapsed Time, > 256 usecs AND <= 512 usecs, 61, or 0.06%Elapsed Time, > 512 usecs AND <= 1024 usecs, 19, or 0.02% Total = 11048 for module tcpip.sysElapsed Time, > 256 usecs AND <= 512 usecs, 2, or 0.02% The GUI shows the following have greater than 0.01% duration:nvlddmkm.sys 0.11%dxgkrnl.sys 0.07%USBPORT.SYS 0.07%tcpip.sys 0.07%ataport.SYS 0.02%ndis.sys 0.02%afd.sys 0.01%VBoxDrv.sys 0.01%ntoskrnl.exe 0.01% And relevant LatencyMon output (taken at a different time of course): Highest DPC routine execution time (µs): 93661.044123Driver with highest DPC routine execution time: nvlddmkm.sys - NVIDIA Windows Kernel Mode Driver, Version 341.44 , NVIDIA Corporation Highest reported total DPC routine time (%): 0.137717Driver with highest DPC total execution time: nvlddmkm.sys - NVIDIA Windows Kernel Mode Driver, Version 341.44 , NVIDIA Corporation Total time spent in DPCs (%) 0.451373 DPC count (execution time <250 µs): 3582912DPC count (execution time 250-500 µs): 0DPC count (execution time 500-999 µs): 7156DPC count (execution time 1000-1999 µs): 1DPC count (execution time 2000-3999 µs): 1DPC count (execution time >=4000 µs): 0 When dwm is maxing out the system is very unresponsive (even typing is jerky) and it's driving me mad. I hate WIn 8 anyway and am half thinking of downgrading to Win 7 but I can't afford the time to do so. Help! Andy